Electrical heating device.



E. H. BUCKLE.

ELECTRICAL HEATING DEVICE.

APPLICATION FILED JUNE 10, 1914.

WMM

@num

,mmnmmllmml @muy UNITED sTATEs PATENT OFFICE.

' EDWARD H. BUCKLE, OF CHICAGO, ILLINOIS, ASSIGNOR TO HUGHES ELECTRICHEATING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. l

ELECTRICAL HEATING DEVICE.

Specitcaton of Letters Patent.

Patented Feb. 16, 1915.

Application led J une 10, 1914. Serial No; 844,128.

Devices, of which the followingis a speciication.

My invention -relates to electrical heating devices particularly to anelectrical hotplate for use on electrical stoves.

Modern hot plates are usually in the form :of supporting blocks ofmaterial which has high heat conductivity and which supports, usually ingrooves, the resistance conductor which is connected-with a currentsupplycircuit. The supporting blocks or plates rapidly absorb the vheatgenerated by the incandescent heating coils and become highly heated. Ascooking utensils are set on or directly over the plate uniform radiationor dissipation of the heat from the block is more or less obstructed.Heat radiates more rapidly from the outer sections of the block as itcan escape around the edges'of the utensil, but at thecentral portion ofthe block the heat is more confined, the result being that this centralportion becomes heated too highly and the utensil is heated more highlyand intensely at its central portion than at its outer portion. Ofcourse, where liquids are heated in the utensil such unequal heating isimmaterial, but where solid material is to be heated, as in frying, thematerial is apt to burn at the center of the pan or uten sil and notreceive suiiicient heat farther away from thecenter.

My invention therefore has for its general object to produceconstruction and arrangement in a heating plate that it will heat moreuniformly.

- More in detail, one important object is to retard, reduce, or preventheating of the central portion. of the block either by omitting heatingwires at such part or by reducing the heat capacity of the wires at suchpart of the block.

Another object is to provide arrangement of the windings which willpermit adjustment of the heating capacity at the central portion of thebloc The object is to accomplish all such heat control and regulationand thereby better heat distribution without decreasing the heatingcapacity of the plate as a whole.

The various features of my invention will be clearly understood byreference to the accompanying drawing in which- Figure 1 is a plan viewofa plate, Fig. 2

is a bottom view thereof, Fig. 3 is a sectional view on plane 33, Fig.1, Fig. 4 is a sectional view on plane i4-4,' Fig. l, and Fig.

5 is a plan view showing a modified arrangement.

On the supporting block 10 two lengths 11 and l2 of spiral heatingconductor are extended back and forth across the plate and adaptedforconnection with a suitable current supply circuit. This principle of theheating coil arrangement is substantially the same as that disclosed inPatent No. 1,068,658, issued July 29, 1913, to George A. Hughes. Theblock is provided in its upper face .with parallel alternate grooves 13and 13 through which the respective conductors 11 and 12 pass back andforth across the plate, the ends of the grooves having passageways 14 tothe back of the block, the respective passageways being connectedtogether by grooves 15 in the under side of the block through which theconductors ass, the conductors being then entirely within the upper andlower faces of the block and thus amply protected. A suitable terminalcontact mechanism 16 is provided for each end of the conductors. Asshown, a terminal screw 17 passes through the block adjacent eachconductor terminal and is threaded to receive nuts 18 for clamping theconductor end and also a lead 19 to the screw.

In accordance with my invention the central part 10 of the block is notprovided with heating conductors on its upper side. In the arrangementof Figs. 1 to 4, the channels 13 and 13 terminate at the central section10 and the conductors in such channels pass to the back of the platethrough passageways 20 and then continue through channels 13a and 13bextending across the under side of the section 10. tinuity of theconductors 11 and 12 is therefore unbroken but the conductors pass alongthe under side of the plate instead of across the top thereof. Theresult of such construction is that the conductor sections 11 and 11Abelow the section 10 have their upward flow of heat retarded by thethick material of section 10 and more uniform distribution over theplate results when a The conductors at the central section.

utensil is thereon, As shown in Fig. 2, the

turns of the conductor sections 1l and 11 may be opened or stretched asdesired in ordervto adjust the' heat capacit 'of the conf theseconductor sections are stretched out suiiiciently very little heat willbe generated, but as the stretch can be c ompensated for by bunching ofthe loops at the ends of the grooves 13 land 13",- the total heatin.capacity of the plate will not be decrease and the continuity of theconductors 11 and 12 is preserved. Thus adjustment can be readily madeto get the vdesired degree 'of heat from the central section to autensil placed over the plate and uniform radiation of heat from theplate to the utensil is assured.

Instead of Vhaving the central portion of the block solid as in Figs. 1to 4, such part couldbe cut away to leave the central opening orpassageway 21 as shown in Fig. 5. The conductor sections 11 and 11extending across the lower end of this opening could then be adjusted bystretching so that the desired heat reduction will be eii'ected. Insteadof leaving passageway 21 entirely open it could be covered by al plate22 which could be of heat insulating material if desired. VThe platecould also serve as a name plate.- Vhere such plate is used a'shoulder23 could be provided for a 'seating therefor. Such removable plate wouldalso allow ready adjustment of the sections 11 and 11 without need ofwithdrawing the entire plate from its support, it being an easy matterto remove the plate and tobring more or less effective length of wireinto the opening 21.

I do not, ofcourse, desire to be limited to the exact construction andarrangement shown as modifications could no doubt be made which wouldstill come within the ,scope of the invention.

I claim the following:

1. In a hot plate for electric stoves, the combination of a. supportingblock, and heating conductors arranged on said block throughout theextent thereof, said conductors at the central section of said platebeing lower than the remaining sections of the conductors whereby theresistance to upward flow of heat from said central section isincreased.

2. A hot plate for electrical stoves comprising a supporting block, acontinuous heating conductor extended back and forth' across the face ofsaid block in parallel sections, the central portions of the middlesections defiecting through and across the bac k.

of the block below the central portion thereof whereby the heat from thecentral portion of the plate will be decreased.

3. A hot plate for electrical stoves comprising a. supporting blockhaving its central portion unchanneled on top but channeled below andhaving channels in its top b etween its central portion and the pe`riphery thereof, said channels below said central portion beingconnected by passageways` with the surface channels adjacent saidcentral portion, and resistance conductor sections arranged in thesurface channels on said block, the sections in the channels adjacentsaid central portion detlecting through said passageways and disposed inthe channels inthe under side of said central portion,v the increaseddistanceof said conductor sections'in'said under side chan-'- nels fromthe top of the'plate serving to retard and decrease the upward radiationof heat from said central portion.

4. I-n a. hotjplate for electrical stoves, the combination of 'asupporting block in the' form of a; circular disk, the upper surface ofsaid block with the exception of4 the central portion thereof beingchanneled, a resistance conductor arranged in said channels, saidresistance conductor detlecting through' the block to the undersidethereof atsaid central portion whereby the upward heat, radiatingeiiciency at the central portion of the block vwill be decreased.

5. A h ot plate for electricstoves comprising a supporting block havingits upper surface with the exception of the central por.- tion thereofchanneled and having the under surface of said central portionchanneled', a heatingconductor'in the form of a continuous coil of wireextended back and forth through said surface channels and delectedadjacent the centralv portion of the -block to extend through said underside Y ing a supporting block having its upper surfacel with theexception'o the central 110 portion thereof channeled and having theunder surface of said central portion channeled, a heating conductor inthe formof a continuous'coil of wire extended back and forth throughsaid surface channels and deflected adjacent the central portion of theblock to extend through said under side channels, the sections of theconductor in said under side channels being stretched to decrease thenumber of turns per unit'length 120 whereby the heating capacity at thecentral section of-the plate is decreased without decreasing the heatingcapacity of the plate as a whole.

l 7. In a hot plate for electrical stoves, the combination of asupporting plate in the form of a circular disk having holestherethrough adjacent its periphery and having holes therethrough aroundits central portion, parallel surface channels connecting channels andbelow the upper surface of the material of said block at saidunchanneled section. f J,

9. In a hot plate for electric stoves, the

combination of a supporting block, and heating conductors passing backand forth on sai section of the block being covered by the material ofthe block and the balance of said conductors bein exposed.

In witness Whereo I hereunto subscribe my name this 6th day of June, A.D., 1914. 20

EDWARD H. BUCKLE. Witnesses:

CHARLES J. SCHMIDT, EDMUND G. INGERsoIm.

block, said conductors at the central 15

